Here's why:

* Focus on Bulk Properties: Thermodynamics deals with the relationships between heat, work, temperature, and other macroscopic properties of systems. It doesn't delve into the microscopic details of individual atoms or molecules.

* Statistical Nature: While the behavior of individual particles influences macroscopic properties, thermodynamics utilizes statistical averages and macroscopic quantities to describe system behavior.

* Equilibrium States: Thermodynamics primarily focuses on systems in equilibrium, where macroscopic properties remain constant over time. This allows for the development of general principles and laws.

However, it's important to note:

* Statistical Mechanics: A related field called statistical mechanics connects the microscopic world to macroscopic phenomena. It uses statistical methods to explain thermodynamic properties based on the behavior of individual particles.

* Nonequilibrium Thermodynamics: This branch of thermodynamics deals with systems that are not in equilibrium. It explores processes like heat transfer, diffusion, and chemical reactions that occur as systems approach equilibrium.

Therefore, while thermodynamics primarily deals with macroscopic processes, its foundation and extensions encompass connections to the microscopic world and non-equilibrium states.